— Are you familiar with the small town?

— Yes. It is just the one _____ I used to work when I was young.   [ ]

A. that    

B. which    

C. what    

D. where

一个地区生态环境的变化和生物多样性的复杂程度呈（）。

A、正相关

B、负相关

C、U型相关

D、倒U型相关